Enhancing the Photocatalytic Activity of CaTaO<sub>2</sub>N for Overall Water Splitting through Surface Nitride Ion Enrichment
Xuecheng Liu, Linjie Yan, Wenpeng Li, Kaihong Chen, Faze Wang, Jiadong Xiao, Takashi Hisatomi, Tsuyoshi Takata, Kazunari Domen
Abstract
Perovskite-type CaTaO 2 N has a band structure suitable for one-step-excitation overall photocatalytic water splitting under visible light. However, the poor electron–hole separation characteristics of this material limit its water splitting activity. In the present work, N-enriched CaTaO 2 N was prepared by sequential nitridation in the presence and then the absence of a flux. The nitride-enriched CaTaO 2 N was found to promote one-step-excitation overall water splitting efficiently and evolved H 2 and O 2 stoichiometrically under visible light with an apparent quantum efficiency of 0.45% at 420 nm. This is the highest value yet reported for a CaTaO 2 N-based material applied to overall water splitting. The increased activity of this photocatalyst is attributed to the incorporation of nitride ions, which enhanced the separation of photogenerated electrons and holes. This study suggests a promising approach to boosting one-step-excitation overall photocatalytic water splitting, using nitride ion enrichment as a means of manipulating charge transfer behavior.